Method and apparatus for transferring data between a host device and plurality of portable computers

ABSTRACT

An electrical system for transferring data concurrently between pen based computers and a host computer includes a multiple computer receptacle device for receiving a plurality of pen based computers. The multiple computer receptacle device includes a housing, and a support frame mounted in the housing for supporting the plurality of pen based computers. The support frame includes a plurality of spaced apart parallel divider panels, where adjacent divider panels define between them a slot for receiving a respective pen based computer. The support frame includes a back panel mounted on the divider panels, a plurality of data input/output connectors mounted on the back panel, and a plurality of power connectors also mounted on the back panel. The data input/output connectors and the power connectors are positioned between adjacent divider panels and are adapted to mate with corresponding data and power connectors mounted on the pen based computers.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to portable computers, and more particularly relates to circuitry which interfaces with portable computers. Even more specifically, this invention relates to a method and apparatus for concurrently transferring data between a host device and a plurality of pen based portable computers.

2. Description of the Prior Art

Pen based computers, which are commonly referred to as electronic clipboards, have become increasingly popular forms of portable computers. Such computers basically include a liquid crystal display and an integral tethered pen for hand-written input of information on the display. The pen based computer may be programmed to display a form or a chart with blanks provided for completion by the user who hand writes the information in the appropriate places on the form displayed. Such pen based computers are particularly adapted for use by non-technically trained personnel, as the user merely has to follow the form or instructions displayed on the computer. These pen based computers may be used by an electric utility, for example, by its meter readers, or may be used in a power plant or manufacturing facility, where gauges may have to be periodically monitored and their readings recorded.

The information inputted by the user to the pen based computer is retained in a memory or storage device in the computer until the data is transferred to a peripheral printer or main computer for analysis or display. The user, who is typically not technically trained, may find it difficult or not understand how to connect the pen based computer to the peripheral equipment or main computer and activate the main computer and pen based computer to output or "dump" the data. If an incorrect procedure is followed in transferring the data, some of the data may be irretrievably lost. Accordingly, either the user must be technically trained to carry out the procedure, or a computer operator must become involved in the data transferring operation.

Furthermore, such data transfer operation usually occurs on an individual basis. That is, only a single pen based computer is connected to the main computer at a time. This, of course, may cause the data transfer operation to take a considerable amount of time, especially when a plurality of pen based computers need to have their data transferred to the main computer.

Similarly, charging the batteries in the pen based computers and transferring data into the pen based computers from the main computer is done on an individual basis, one computer at a time.

OBJECTS AND SUMMARY OF THE INVENTION

It is an object of the invention to provide a method and apparatus for transferring data concurrently from a plurality of portable computers.

It is another object of the present invention to provide apparatus for receiving a plurality of pen based computers and for transferring data between a main computer and the pen based computers.

It is a further object of the present invention to provide apparatus for holding a plurality of portable computers and for automatically attending to housekeeping functions with respect to the portable computers, such as file management, and charging the batteries of the portable computers or loading data into the portable computers.

It is still a further object of the present invention to provide a method and apparatus for transferring data concurrently from a plurality of portable computers and for checking the data transferred from the computers for accuracy.

It is yet another object of the present invention to provide an electrical system for transferring data signals concurrently between a host device and a plurality of pen based portable computers.

In one form of the present invention, apparatus (also referred to herein as a multiple computer receptacle device) for transferring data from a plurality of pen based computers includes a housing and a plurality of spaced apart parallel divider panels situated within the housing. Adjacent divider panels define between them a slot for receiving a respective pen based computer.

The apparatus further includes a back panel. The back panel is mounted in the housing and disposed transversely to the divider panels. A plurality of data input/output connectors are further included. The data connectors are floatingly mounted on the back panel and positioned between adjacent divider panels so as to be adapted to mate with corresponding data connectors mounted on the pen based computers.

The apparatus also includes a plurality of power connectors. The power connectors are floatingly mounted on the back panel and positioned between adjacent divider panels so as to be adapted to mate with corresponding power connectors mounted on the pen based computers.

In a preferred form of the invention, the apparatus for transferring data further includes a plurality of Teflon (TM) or Delrin (TM) guide brackets. Each of the guide brackets is situated adjacent to a divider panel within a respective slot defined by adjacent divider panels. The guide brackets engage an edge of the pen based computers to facilitate insertion of the pen based computers into respective receiving slots.

Also, the apparatus may include a plurality of anti-friction strip members. The anti-friction strip members are mounted on the divider panels. The strip members have a surface which is exposed within the computer receiving slot for engagement with a pen based computer situated in the slot.

In an alternative form of the invention, the apparatus may include top and bottom plates mounted in the housing. The plates have formed in them recesses to define channels for receiving the pen based computers.

In a further aspect of the present invention, an electrical system for transferring data concurrently between at least one pen based computer received by a multiple computer receptacle device and a main data gathering and dispatching circuit (also referred to herein as a host device) includes a first signal generator, the first signal generator being situated on the multiple computer receptacle device. The first signal generator provides a first signal indicating that at least one pen based computer is received by the multiple computer receptacle device. The multiple computer receptacle device defines a plurality of slots for receiving a plurality of pen based computers.

The electrical system further includes a second signal generator which is responsive to the first signal. The second signal generator is situated on the main data gathering and dispatching circuit and provides a second signal to the multiple computer receptacle device to determine which one of the slots of the multiple computer receptacle device has the pen based computer.

The electrical system further includes a first memory for storing a plurality of logic identification codes. The first memory is situated on the main data gathering and dispatching circuit and has stored therein a plurality of logic identification codes. Each identification code corresponds to one of the plurality of pen based computers.

The electrical system further includes a third signal generator. The third signal generator is situated on the main data gathering and dispatching circuit and provides a third signal to the multiple computer receptacle device. The third signal corresponds to at least one of the identification codes stored in the first memory.

A second memory is also included. The second memory is situated on the pen based computer and has stored therein a predetermined identification code which corresponds to the pen based computer.

A third signal receiver and comparator circuit is situated on the pen based computer. The receiver and comparator circuit receives the third signal and compares logic data corresponding to the third signal with the predetermined identification code stored in the second memory.

The pen based computer also includes a third memory for storing logic data inputted to the computer by a user of the computer. The third memory is situated on the computer. A transmitter is coupled to the third memory and transmits first data signals which correspond to the logic data stored in the third memory. The first data signals are transmitted to the main data gathering and dispatching circuit.

A receiver on the main data gathering and dispatching circuit receives the first data signals, and a fourth memory on the main data gathering and dispatching circuit stores the first data signals as logic data. Thus, this logic data represents information which the user of the pen based computer inputs to the computer. This data is accordingly transferred to the main data gathering and dispatching circuit, where it can be later displayed or utilized by the operator of the main data gathering and dispatching circuit.

Data can also be transferred from the main data gathering and dispatching circuit to the individual pen based computers received by the multiple computer receptacle device. For this purpose, a fifth memory is situated on the main data gathering and dispatching circuit for storing logic data inputted to the circuit by an operator of the circuit. The main data gathering and dispatching circuit further includes a transmitter for transmitting second data signals to the pen based computers and received by the multiple computer receptacle device, the second data signals corresponding to the logic data stored in the fifth memory.

The pen based computer includes a receiver for receiving the second data signals, and a sixth memory for storing logic data corresponding to the second data signals dispatched to the pen based computer by the main data gathering and dispatching circuit.

The electrical system further includes a keyboard which is coupled to the main data gathering and dispatching circuit so that data may be inputted to the dispatching circuit by an operator.

The first through sixth memories mentioned previously may be separate memories or may form portions or "slots" of single memory circuits respective to the pen based computers and the main data gathering and dispatching circuit. Furthermore, the individual components mentioned previously, such as the signal receivers, signal generators and memories, may be realized by circuitry existing on each pen based computer and programmed to perform that particular function described above. Each pen based computer contains a random access memory (RAM) or a RAM card having a RAM (random access memory) which may be programmed so that the pen based computers will perform the desired functions. Similarly, the main data gathering and dispatching circuit may be formed from individual components, such as the signal generators, signal receivers and memories described previously, or may be a host computer which is programmed to perform the functions described above.

In a preferred form of the invention, the electrical system for concurrently transferring data between the pen based computers and the main data gathering and dispatching circuit may include a charge and discharge circuit. The charge and discharge circuit is preferably mounted on the multiple computer receptacle device and is coupled to the power supply of each pen based computer received by the receptacle device. Since most pen based computers operate with nickel cadmium (Ni-Cad) batteries, it is well known to fully discharge the batteries before recharging them in order to prolong their life and cycle depth. The charge and discharge circuit of the present invention senses the charge remaining on the battery of each pen based computer received by the multiple computer receptacle device and, after the data transfer operation has been completed, automatically discharges the batteries of the pen based computers to a predetermined level and, subsequently, recharges the batteries to a second predetermined level so that the pen based computers will be ready for use.

These and other objects, features and advantages of the present invention will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a system formed in accordance with the present invention for transferring data between a plurality of pen based computers and a host device or main data gathering and dispatching circuit.

FIG. 2 is a front perspective view of a multiple computer receptacle device formed in accordance with the present invention.

FIG. 3 is a front perspective view of the multiple computer receptacle device shown in FIG. 2 and illustrating the insertion of pen based computers into the receptacle device.

FIG. 4 is a rear perspective view of the multiple computer receptacle device shown in FIG. 2.

FIG. 5 is a block diagram of an electrical system for transferring data concurrently between a main data gathering and dispatching circuit and a plurality of pen based computers, in accordance with the present invention.

FIGS. 6A-6C are an alternative form of an electrical system of the present invention for transferring data concurrently between a main data gathering and dispatching circuit and a plurality of pen based computers.

FIGS. 7a-7h are a flow chart illustrating the operation of the electrical system of the present invention.

FIG. 8 is a partially broken away, perspective view of an alternative form of a multiple computer receptacle device formed in accordance with the present invention.

FIG. 9 is a block diagram of an alternative form of a main data gathering and dispatching circuit formed in accordance with the present invention.

FIG. 10 is a pictorial illustration of an alternative form of an electrical system for transferring data between a plurality of pen based computers and other components, formed in accordance with the present invention.

FIGS. 11a-11h are a flow chart illustrating the operation of an alternative form of the electrical system of the present invention.

FIG. 12 is a perspective view of a battery pack charging rack formed in accordance with the present invention.

FIG. 13 is a block diagram of a charge and discharge circuit formed in accordance with the present invention and for use with the electrical system of the present invention.

FIGS. 14A-14D are a schematic diagram of the charge and discharge circuit shown in block diagram form in FIG. 13.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention allows a plurality of pen based computers to be electrically coupled to a host device such as a computer or a main data gathering and dispatching circuit so that the data stored in the memory of the pen based computers may be transferred concurrently to the host device rather than each pen based computer individually transferring its data to a host device. The present invention also allows data to be transferred to each of the pen based computers.

As an example of one application of the present invention, a utility may use the system and issue each of its meter readers one pen based portable computer. In performing their duties, the meter readers input data into the pen based computers regarding the electrical power or gas consumption of different residences or locations, which residence addresses are preprogrammed into the pen based computer. At the end of the day, the utility meter reader inserts his pen based computer into a multiple computer receptacle device, which will be described in greater detail. The multiple computer receptacle device is coupled to a host computer or main data gathering and dispatching circuit. After normal business hours, the system of the present invention will automatically transfer the data inputted by the meter readers to the pen based computers to the host computer or device. The host computer will also transfer data, such as a new list of residences to be checked for power consumption, to each pen based computer. The system of the present invention will also attend to housekeeping functions with regard to the pen based computers, such as recharging the nickel-cadmium batteries of the pen based computers.

The next morning, the meter readers will remove their pen based computers from the multiple computer receptacle device, each pen based computer having been reprogrammed with a new listing of residences to check for power consumption. The pen based computer batteries will also be recharged and ready for use.

Referring initially to FIGS. 1-4 of the drawings, it can be seen that the electrical system of the present invention includes a main data gathering and dispatching circuit 2 in the preferred form of a host computer, and a multiple computer receptacle device 4 coupled to the host computer 2. The host computer 2 preferably includes a display 6 and a keyboard 8 for entering data into the host computer by an operator. The host computer 2 is coupled to the multiple computer receptacle device 4 through a plurality of data signal cables 10.

A plurality of pen based computers 12 are received by the multiple computer receptacle device 4. A typical pen based computer 12 is illustrated by FIG. 3. The pen based computer typically includes an integral tethered pen (not shown) for handwriting input. A suitable pen based computer which may be used with the electrical system of the present invention is a Grid Pad (TM) computer manufactured by Grid Systems Corporation in Fremont, Calif.

The multiple computer receptacle device 4 basically includes a housing 14 having opposite side walls 16 on which are mounted slide brackets 18. A chassis or support frame 20 for the pen based computers is mounted on the slide brackets 18 within the housing. The support frame 20 may be slidably removed from the housing 14 to allow access to the circuitry and connectors mounted on the frame, as will be explained.

The support frame 20 includes a plurality of spaced apart parallel divider panels 22. Adjacent divider panels 22 define between them a slot 24 for receiving a respective pen based computer 12. An inner back panel 26 is mounted to the rear edges of the divider panels 22 and is disposed transversely to the divider panels. The inner back panel 26 includes a plurality of data input/output connectors 28. The input/output connectors 28 are mounted on the inner back panel with a floating mount and positioned between adjacent divider panels 22 so that they are adapted to mate with a corresponding data connector mounted on the pen based computers received by the slots 24 of the multiple computer receptacle device.

Also, a plurality of power connectors 30 are mounted on the inner back panel 26 using a floating mount. The power connectors 30 are also positioned between adjacent divider panels 22 so as to be adapted to mate with a corresponding power connector mounted on each pen based computer.

The support frame 20 of the multiple computer receptacle device further includes an outer back panel 32 which is spaced apart and parallel to the inner back panel 26. The outer back panel 32 includes a plurality of connectors 34 which are electrically coupled to the corresponding data connectors 28 mounted on the inner back panel 26 and which further include cables 10 which are coupled to the host computer 2 or main data gathering and dispatching circuit, as will be described. An AC line voltage power connector 38 is also mounted on the outer back panel 32 of the support frame. AC power is provided to the multiple computer receptacle device to power the electronic circuitry mounted on the device, as will be explained. The electronic circuitry is preferably disposed in the spacing between the inner and outer back panels 26, 32.

A plurality of Teflon (TM) or Delrin (TM) guide brackets 4 are preferably mounted in the slots 24 which receive the pen based computers. More specifically, each of the guide brackets 40 is mounted on a divider panel 22 within a respective slot. The guide brackets 40 are preferably L-shaped in cross section, and include an exposed surface which engages an edge of the pen based computers to facilitate insertion of the pen based computers 12 into respective receiving slots.

A plurality of anti-friction strip members 42 are also preferably included. The anti-friction strip members 42 are mounted on the divider panels 22 and include an exposed surface within the pen based computer receiving slot 24 in which they are mounted for engagement with a pen based computer situated in the slot. The anti-friction strip members 42 also facilitate the insertion of the pen based computers into their respective receiving slots in the multiple computer receptacle device and, like brackets 40, may also be formed from a Teflon (TM) or Delrin (TM) material.

In a preferred form, the multiple computer receptacle device 4 also includes a transparent dust cover 44 which is mounted on the support frame 20 by hinges (not shown) and pivotable to cover and uncover the open ends of the receiving slots 24. A latch or other mechanism 46 may be mounted on the dust cover 44 and engageable with a surface of the support frame 20 to ensure that the dust cover remains in the closed position covering the slots 24 and the pen based computers 12 mounted in the multiple computer receptacle device.

The multiple computer receptacle device 4 illustrated by FIGS. 2 and 3 of the drawings is designed to accept eight pen based computers 12. However, it is envisioned to be within the scope of the invention to construct a multiple rack-type housing having a plurality of sliding brackets, which housing is adapted to receive a number of computer support frames, as described, in a vertical arrangement. Accordingly, a multiple computer receptacle device may be constructed to accept 32 pen based computers, for example, in four vertical sections (such as device 386 shown in FIG. 10), and such a device may be expandable to accept additional pen based computers as demand requires.

An electrical system for transferring data concurrently from a plurality of pen based computers 12 to a host device or a main data gathering and dispatching circuit 2 will now be described. One form of the electrical system is illustrated by the block diagram of FIG. 5. The basic system includes a main data gathering and dispatching circuit 2 (or, alternatively, a host computer), the multiple computer receptacle device 4, as previously described, and the pen based computers 12. The main data gathering and dispatching circuit 2 is coupled to the pen based computers mounted in the multiple computer receptacle device through the mating data connectors 28 of the multiple computer receptacle device 4.

The electrical system first includes a first signal generator 50. The first signal generator 50 is situated on the multiple computer receptacle device 4. The first signal indicates when one or more pen based computers 12 are received by the multiple computer receptacle device. In its most simplest form, the first signal generator 50 may be a push button switch 51 mounted on the multiple computer receptacle device. When the operator has loaded one or more pen based computers into the receptacle device 4, he presses the switch which sends the first signal to the main data gathering and dispatching circuit 2.

The main data gathering and dispatching circuit 2 includes a second signal generator 52 which, in response to the first signal, provides a second signal to the multiple computer receptacle device 4. The second signal is provided for determining which one of the slots 24 of the multiple computer receptacle device has a pen based computer mounted in it. The pen based computers 12 include a second signal receiver 54 to receive this signal, and a return signal generator 56 to generate a return signal to the main data gathering and dispatching circuit 2, which includes a return signal receiver 57, so that the main data gathering and dispatching circuit can recognize which slot 24 of the multiple computer receptacle device 4 has a pen based computer mounted in it.

The main data gathering and dispatching circuit 2 further includes a first memory 58 for storing a plurality of logic identification codes. More specifically, a list of identification codes are stored in the memory 58, each identification code corresponding to one of a plurality of pen based computers 12.

The main data gathering and dispatching circuit 2 further includes a third signal generator 60 which is coupled to the first memory 58 and which provides a third signal to the multiple computer receptacle device 4, the third signal corresponding to at least one of the identification codes stored in the first memory.

Each pen based computer 12 includes a second memory 62. The second memory 62 stores a predetermined logic identification code which is preprogrammed and specific to each pen based computer. A third signal receiver 64 situated on each pen based computer receives the third signal corresponding to the identification codes stored in the first memory 58 of the main data gathering and dispatching circuit, and compares logic data corresponding to this third signal with the predetermined identification code stored in the second memory 62 of the pen based computer. If the two identification codes match, the transfer of data between the pen based computer 1 and the main data gathering and dispatching circuit 2 will proceed.

Each pen based computer 12 further includes a third memory 66 for storing logic data inputted to the pen based computer by a user of the computer. As in the case of the utility, for example, the meter reader will input the gas or electric meter readings by using the tethered pen of the pen based computer. This data corresponding to the meter readings will be stored in the third memory 66.

A transmitter 68 situated on the pen based computer 12 will transmit first data signals corresponding to the logic data stored in the third memory 66 to the main data gathering and dispatching circuit 2. A receiver 70 on the main data gathering and dispatching circuit will receive the first data signals and store the signals as logic data in a fourth memory 72 constituting part of the main data gathering and dispatching circuit. Accordingly, the data from the pen based computers 12 is transferred to the main data gathering and dispatching circuit 2 or host computer for further processing or analysis.

The electrical system of the present invention further has the capability of transferring data from the host computer or main data gathering and dispatching circuit 2 to one or more of the pen based computers 12 mounted in the multiple computer receptacle device 4. In the case of an electric or gas utility, for example, each pen based computer 12 may be programmed by the host computer or main data gathering and dispatching circuit 2 with a list of residences to be checked by the meter reader the following business day. To input data to the main data gathering and dispatching circuit 2, a keyboard 8 is included and coupled to the circuit.

Accordingly, the main data gathering and dispatching circuit 2 includes a fifth memory 74 for storing logic data inputted to the main data gathering and dispatching circuit by an operator, and a transmitter 76 coupled to the fifth memory 74 for transmitting second data signals corresponding to the logic data stored in the fifth memory 74 to the pen based computers.

The pen based computers include a receiver 78 for receiving the second data signals, and a sixth memory 80 coupled to the receiver 78 for storing logic data corresponding to the second data signals provided to the pen based computers by the main data gathering and dispatching circuit.

A more preferred form of the electrical system for transferring data between a plurality of pen based computers 12 and a main data gathering and dispatching circuit or host device 2 is illustrated in block diagram form in FIGS. 6A-6C. The multiple computer receptacle device 4 more preferably includes a charge and discharge circuit 100, as will be described, which interfaces with the pen based computers mounted in the receptacle device and the main data gathering and dispatching circuit. The receptacle device 4 further includes a first signal generator 102, which may be a switch, as described previously in relation to the embodiment illustrated by FIG. 5. The main data gathering and dispatching circuit 2 includes a first signal receiving circuit 104, which circuit provides an output signal in response to the first signal. As mentioned previously with respect to the embodiment shown in FIG. 5, the first signal indicates that at least one pen based computer is received by the multiple computer receptacle device 4.

After receiving the first signal and in response thereto, the main data gathering and dispatching circuit generates a second signal. For this purpose, the data gathering and dispatching circuit 2 includes a second signal generating circuit 106. The purpose of the second signal is to poll the pen based computers 12 for determining which slot 24 of the multiple computer receptacle device 4 has a pen based computer mounted in it, and for performing a security check. The second signal, which is a polling and security check signal, is preferably an eight bit digital word.

The pen based computers 12 include a second signal receiving circuit 108 and, in response to the second signal, generate an output signal which is provided internally to a third signal generating circuit 110 situated on the pen based computer. The third signal generating circuit 110, in response to the output signal from the second signal receiving circuit 108, generates a third signal and provides the third signal to the main data gathering and dispatching circuit 2. The purpose of the third signal, like the second signal, is for polling the main data gathering and dispatching circuit and for performing a security check with respect thereto. The third signal, like the second signal, is preferably an eight bit word. The second and third signals are, in effect, redundant signals and ensure that the main data gathering and dispatching circuit 2 is communicating with the proper pen based computers 12, and that the pen based computers are communicating with the proper main data gathering and dispatching circuit. Stated another way, the second signal, in effect, informs the pen based computers 12 that the main data gathering and dispatching circuit 2 is communicating with them, and the third signal is effectively a signal to the main data gathering and dispatching circuit 2 that a pen based computer is in one of the slots of the multiple computer receptacle device 4 and communicating with the main data gathering and dispatching circuit. The third signal may have the same, but preferably different, decimal equivalent of the second signal.

The main data gathering and dispatching circuit includes a third signal receiving circuit 112 which will generate an output signal if the third signal is received. The output signal is provided to a display 6 coupled to the main data gathering and dispatching circuit, which display 6 will display the message "logging in" or its equivalent, to inform the operator that there are pen based computers in the receiving slots 24 of the multiple computer receptacle device 4. The display 6 will display a column of slot numbers, and next to each slot number will display either the "logging in" message or an "empty" message, to indicate that a pen based computer 12 is received or not received by a particular slot 24 of the multiple computer receptacle device.

If no third signal is received by the main data gathering and dispatching circuit 2, the main data gathering and dispatching circuit will disconnect electrically from the pen based computer with which it is trying to communicate. This may occur if no pen based computer is mounted in a respective slot 24 of the multiple computer receptacle device. However, the main data gathering and dispatching circuit will continue to send out the second signal to the empty slot 24 until the third signal is received.

In response to the third signal, the third signal receiving circuit 112 generates an output signal and provides that output signal to a fourth signal generating circuit 114. The fourth signal generating circuit 114, situated on the main data gathering and dispatching circuit 2, will generate a fourth signal, preferably a forty bit word, and provide this signal to the pen based computers through the multiple computer receptacle device.

The forty bit fourth signal corresponds to an identification/password code. Each pen based computer 12 is preprogrammed with a particular identification/password code, and communication between the pen based computer and the main data gathering and dispatching circuit will continue only if the two identification/password codes match.

More specifically with regard to the exchange of password/identification codes, the main data gathering and dispatching circuit 116 includes a first look-up table memory circuit which is coupled to the fourth signal generating circuit 114. The first look-up table memory circuit 116 has stored therein logic data corresponding to a plurality of the identification/password codes (the "first" codes). Each of the first identification/password codes corresponds to a respective pen based computer 12. The first look-up table memory circuit 116 essentially includes a list of the first identification/password codes, and the main data gathering and dispatching circuit sends these first identification codes as signals to the multiple computer receptacle device 4 and to each of the pen based computers 12 mounted in the slots of the receptacle device.

Each pen based computer 12 includes a fourth signal receiving and comparator circuit 118, and a second look-up table memory circuit 120. Stored in the second look-up table memory circuit 120 is logic data which corresponds to an identification/password code which is unique for each computer (the "second" code). Each pen based computer is preprogrammed with the second identification/password code. The second look-up table memory circuit 120 is electrically coupled to the fourth signal receiving and comparator circuit 118. The fourth signal receiving and comparator circuit compares the second identification/password code logic data stored in the second look-up table memory circuit 120 with the fourth signal corresponding to the first identification code. If the first and second identification/password codes are the same, the comparator circuit 120 generates an output signal to a fifth signal generating circuit 122 located on the pen based computer.

The fifth signal generating circuit 122 provides a fifth signal in response to the output signal of the fourth signal receiving and comparator circuit 118. The fifth signal corresponds to the second identification/password code logic data stored in the second look-up memory circuit 120.

The fifth signal is received by a fifth signal receiving and comparator circuit 124 situated on the main data gathering and dispatching circuit. The fifth signal receiving and comparator circuit 124 compares the first identification/password code logic data stored in the first look-up table memory circuit 116 with the fifth signal corresponding to the second identification code, and provides an output signal in response thereto. In effect, the second identification/password codes (i.e., the fifth signal) sent by the pen based computers to the main data gathering and dispatching circuit are checked against the list of first identification/password codes stored in the first look-up table memory circuit 116. If a particular pen based computer's identification/password code is not located in the first look-up table memory circuit, communications between that pen based computer and the main data gathering and dispatching circuit will cease, except that the output signal from the fifth signal receiving and comparator circuit 124 is provided to the second signal generating circuit 122 which continues to send out a polling and security check signal (i.e., the second signal) to the pen based computer, in effect, to reinitiate communications between the pen based computer 12 and the main data gathering and dispatching circuit 2.

If the second identification/password code (i.e., the fifth signal) from a particular pen based computer matches a first identification/password code stored in the first look-up table memory circuit 116 of the main data gathering and dispatching circuit, a new identification/password code is selected for that particular pen based computer. An identification/password selection circuit 126 which, for example, may be a random number generator, is situated on the main data gathering and dispatching circuit and is electronically coupled to the first look-up table memory circuit 116. The identification/password selection circuit 126 will replace a previously used second identification/password code in the first look-up table memory circuit 116 with a new identification/password code.

The main data gathering and dispatching circuit includes a sixth signal generating circuit 128 which is coupled to the identification/password selection circuit 126 to provide the sixth signal, which corresponds to the new identification/password code, to a respective pen based computer 12. Each pen based computers includes a sixth signal receiving circuit 130 which provides an output signal in response to the sixth signal which it receives, the output signal corresponding to the new identification/password code. The output signal is provided to the second look-up table memory circuit 120, and the second look-up table memory circuit stores the output signal corresponding to the new identification/password code as logic data in substitution for the second identification/password signal logic data previously stored in the memory circuit 120.

After this initial polling and identification stage in the operation of the electrical system of the present invention, the pen based computers 12 are now ready to transfer data which has been inputted to the pen based computers to the main data gathering and dispatching circuit or host computer 2. To carry out this operation, each pen based computer includes a first data memory circuit 132. The first data memory circuit 132 has stored in it the logic data inputted to the pen based computer by the user.

Each pen based computer also includes a first data transmission circuit 134. The first data transmission circuit 134 is electrically coupled to the first data memory circuit 132 and is provided for transmitting first data signals corresponding to the logic data stored in the first data memory circuit to the main data gathering and dispatching circuit 2. Preferably, the first data signals are transmitted by the first data transmission circuit 134 twice, that is, a first time and a second time.

The main data gathering and dispatching circuit includes a first data receiving circuit 136. The first data receiving circuit 136 receives the first data signals and provides the first data signals to a first data buffer memory circuit 138 situated on the main data gathering and dispatching circuit. The first data buffer memory circuit 138 is coupled to the first data receiving circuit 136 and stores therein the first data signals transmitted twice to the main data gathering and dispatching circuit. Two files are set up in the first data buffer memory circuit 138. The first file contains the logic data corresponding to the first data signals transmitted the first time, and the second file includes the logic data corresponding to the first data signals transmitted the second time.

A first file length and content check circuit 140 is also included in the main data gathering and dispatching circuit 2. The first file length and content check circuit 140 is coupled to the first data buffer memory circuit 138, and compares the logic data in the first file with the logic data in the second file.

Both the file length and the content of the two files are compared. Based upon this comparison, an output signal is provided by the check circuit 140 to the display 6 to present the message "receiving" on the display to indicate that data is incoming from the pen based computers.

The main data gathering and dispatching circuit includes a seventh signal generating circuit 142 which is coupled to the first file check circuit 140. If the file length and content of the two files are the same, the content of the sixth signal is such that it will instruct the particular pen based computer to erase the data stored in its first data memory circuit 132. If the file length or content of the two files are not the same, the particular content of the sixth signal will instruct the pen based computer to retransmit the data stored in the first data memory circuit 132. Accordingly, each pen based computer includes a seventh signal receiving circuit 144 which is coupled to the first data transmission circuit 134 and to the first data memory circuit 132 and which is adapted to receive the seventh signal and to instruct the pen based computer to either erase the data stored in the first data memory circuit or to retransmit the data.

As mentioned previously with respect to the embodiment illustrated by FIG. 5, the present embodiment has the capability of transmitting data from the main data gathering and dispatching circuit or host computer 2 to the individual pen based computers 12 loaded into the multiple computer receptacle device 4. This data is inputted to the host computer or main data gathering and dispatching circuit by a keyboard 8 which is connected through an input/output circuit 144 to a second data memory circuit 146 situated on the main data gathering and dispatching circuit and in which is stored the outgoing data (also referred to herein as the second data). The second data memory circuit 146 is coupled to a second data transmission circuit 148 also situated on the main data gathering and dispatching circuit, which is further coupled to the first look-up table memory circuit 116. As stated previously, the first look-up table memory circuit 116 has stored therein a list of identification/password codes for the pen based computers. Along with each identification/password code may be stored a flag for a particular pen based computer, which flag indicates that data is to be transmitted to that particular pen based computer. The flag will cause the main data gathering and dispatching circuit 2 to transmit data to the particular pen based computer that is flagged.

The outgoing or second data from the main data gathering and dispatching circuit 2 is received by a second data receiving circuit 150 situated on each pen based computer. Each pen based computer also includes a second data buffer memory circuit 152 which is coupled to the second data receiving circuit 150 and which stores as logic data the second data signals transmitted by the second data transmission circuit 148.

In the same manner that the incoming data is transmitted from the pen based computer to the main data gathering and dispatching circuit, the outgoing or second data is transmitted twice, that is, a first time and a second time. Two files are set up in the second data buffer memory circuit 152, the first file storing logic data corresponding to the first transmission of the outgoing data, and the second file storing logic data corresponding to the second transmission of the outgoing data.

A second file length and content check circuit 154 is also included and situated on each pen based computer. The second file length and content check circuit 154 is coupled to the second data buffer memory circuit 152 and compares the length and content of the first file with those of the second file, and provides an output signal in response to this comparison. The output signal is provided to an eighth signal generating circuit 156 situated on the pen based computer. If the length and the content of the files in the second data buffer memory circuit 152 correspond, then the content of the eighth signal is such that it verifies that the outgoing or second data has been correctly received by the pen based computer. If the two files do not correspond, then the content of the eighth signal is such that it signals the main data gathering and dispatching circuit to resend the outgoing data.

The main data gathering and dispatching circuit includes an eighth signal receiving circuit 158 which, in response to the specific content of the eighth signal, will cause the outgoing data to be resent or proceed with the data transfer operation. The output signal is further provided to the display 6 to signal the display to present the message "verifying data", to inform the operator that the outgoing data is being checked to see if it was properly received.

If the first and second files in the second data buffer memory circuit 152 of the pen based computer match each other, then the output signal of the eighth signal receiving circuit 158 of the main data gathering and dispatching circuit is provided to a ninth signal generating circuit 160 on the main data gathering and dispatching circuit. The ninth signal is a "disconnect" signal which is provided to the pen based computer and which is received by a ninth signal receiving circuit 162 situated on the pen based computer. The ninth signal receiving circuit 162 provides an output "disable" signal to the second signal receiving circuit 108 on the pen based computer to disconnect the communication between the particular pen based computer and the main data gathering and dispatching circuit or host computer 2. The ninth signal is also provided to the display 6 so that the display will present the message "complete" to indicate to the operator that the operation of the electrical system for transferring data has been completed.

As mentioned previously, the charge and discharge circuit 100 mounted on the multiple computer receptacle device 4 is coupled to the power supply or battery pack of each pen based computer through the power connectors 30. The circuit is also connected to the first signal generating circuit 102 of the multiple computer receptacle device and to the ninth signal generating circuit 160 of the main data gathering and dispatching circuit. The first signal is provided to the charge and discharge circuit 100. When the pen based computers are mounted in the multiple computer receptacle device 4, the charge and discharge circuit 100 will provide power to the pen based computer in response to the first signal.

At the end of the transfer of data between the pen based computers 12 and the main data gathering and dispatching circuit 2, the charge and discharge circuit 100 will discharge the power supply or battery pack 164 of each pen based computer in response to the ninth or "disconnect" signal. The purpose is to discharge the nickel-cadmium batteries in the pen based computer battery pack to a predetermined level which is sensed by the discharge and recharge circuit 100. When the nickel-cadmium batteries have bee discharged to this level, the charge and discharge circuit will recharge the batteries of the pen based computers until a second predetermined voltage level is sensed by the circuit. Thus, the pen based computers will be fully recharged and ready for use. A preferred form of the charge and discharge circuit is shown in FIGS. 13 and 14 and will be described later in greater detail.

With reference to the flow chart illustrated by FIG. 7, the operation of the system for transferring data concurrently between the pen based computers and the main data gathering dispatching circuit or host computer will now be described.

After the pen based computers 12 ar loaded into the multiple computer receptacle device 4, the operator activates the switch on the multiple computer receptacle device, which sends the first signal to the host device 2, indicating that the pen based computers are received by the multiple computer receptacle device (Block 200). The first signal also activates the charging circuit 100 to providing power to the pen based computers mounted in the multiple computer receptacle device (Block 202).

If the first signal is not received by the host device (Block 204), the host computer will wait for the first signal. If the signal is received, the host device sends out the second signal to the pen based computers (Block 206).

The display 6 displays a listing of the slots of the multiple computer receptacle device 4. After the host device sends out the second signal, the message "active" is displayed next to each slot number (Block 208).

The pen based computers received by the multiple computer receptacle device are in a continuous loop waiting for the second signal (Block 210). If the second signal is received by the pen based computers, then each pen based computer will send a third signal to the host device (Block 212).

The host device is in a continuous loop waiting for the third signal (Block 214) If the host device receives the third signal, then it compares the third signal with that which is stored in memory (Block 216). The second and third signals are the polling and security check signals, preferably eight bits each, described previously. In one form of the invention, each of the pen based computers sends out the same polling and security check signal (i.e., the third signal) to the host device. The host device will compare the third signal received from the pen based computers with what it has stored in memory (Block 216). If the third signal does not match that which is stored in memory, the host device will exit the operational routine. If the two match, the host device will update the display screen with the message "logging in" next to the particular pen based computer slot number from which a third signal is received (Block 218).

The host device next sends out a 40 byte identification/password signal to the pen based computers (Block 220). Each pen based computer has its own identification/password code, which the host device looks up from the look-up table and determines if this identification/password code matches that which is received from the host device (Block 222). If there is no match between the two identification/password codes, the pen based computer will exit its operational routine. If there is a match, then the pen based computer will send to the host device a 40 byte user identification/password signal which is particular to each pen based (Block 224).

The host device receives this 40 byte user identification/password signal, and compares it to a list of identification/password codes which are stored in its look-up table memory (Block 226). If the identification/password code received by the host device is not found in the look-up table memory of the host device, the host device will return to that portion of the operational routine where it will send out the second "polling" signal to the pen based computer (Block 206). If the user identification/password code from the pen based computer is included on the list of codes stored in the look-up table memory, the host device will update the look-up table memory to change that particular pen based computer's user identification/password code (Block 228), and will send a new user identification/password code to the pen based computer (Block 230). The pen based computer will update its look-up table with the new user identification/password code (Block 232). This step completes the log-in phase of the operational routine.

The host device then sends a signal to the pen based computer requesting the file length of data which is stored in the pen based computer memory (Block 234). The host device also updates the display so that the message "receive file length" is displayed next to the slot number of the particular pen based computer with which it is communicating (Block 236).

In response to the signal received from the host device, the pen based computer checks the file length of the data stored in its memory, and returns a 16 byte signal in the form of an encoded character string incorporating the file length information (Block 238). The host device decodes the 16 byte word and puts the file length data in a first file length slot of its memory (Block 240).

For redundancy, the pen based computer checks the file length and returns another 16 byte signal, as it did in Block 238 (Block 242), and the host device decodes the second 16 byte word, as it did in Block 240 and puts the file length data extracted from the 16 byte word in a second file length slot of memory (Block 244).

The host device then compares the file length in the first slot of its memory with the file length in the second slot (Block 246). If the two file lengths do not match, the host device will return to Block 234 of its operational routine and will send a signal to the pen based computer again requesting the file length of the data stored in its memory. If the two file lengths are the same, it will then check to see if the file length is equal to zero (Block 248). If the file length is equal to zero, which indicates that there is no data stored in the pen based computer, the host device will skip the data retrieval portion of the operational routine and advance to the routine corresponding to transferring new data to the pen based computer. If the file length is not equal to zero, indicating that there is data to be transferred to the host device, the host device will send out a signal to transfer the data from the pen based computer to the host device (Block 250). The host device will then cause the message "receive 1" to be displayed next to the slot of the particular pen based computer with which it is communicating (Block 252), indicating that data is being transferred from the pen based computer to the host device a first time. The pen based computer then sends the data over to the host device (Block 242).

So that the operator of the system for transferring data can monitor the progress of the data transfer operation, the host device will cause a segment or incremental gauge to be displayed. The host device will compare the data which is being received with the file length, and determines if all the data has been received (Block 256). The host device will then calculate the percentage of the data which has been received (Block 258) and will display the number of segments of the segmented display corresponding to that percentage of the data which is received (Block 260). The host device will continue to update the display in this manner until all the data is received. The host device will then put the data into its buffer memory in what shall be designated for convenience Slot No. 1 (Block 262). The host device will then compute the file length of Slot No. 1 (Block 264), and compare the file length which it just computed with the file length stored in the first file length slot (Block 266). If the file lengths are not the same, the host device will return to that portion of the operational routine where it will send out a signal to the pen based computer to transfer data to the host device (Block 250). If the two file lengths are equal, the host device will send out a second signal to the pen based computer to transfer the data from the pen based computer to the host device a second time (Block 268). The host device will cause the message "receive 2" to be displayed next to the slot number of the particular pen based computer with which it is communicating (Block 270).

The pen based computer will then send its data over to the host device for a second time (Block 270), as it did in Block 254. The host device will again cause a "gas gauge" type of segment display to be shown on the display 6 and calculate the percentage of data being received for a second time, and continually update the display until all of the data is received, as it did in Blocks 256-260 (Blocks 274-278).

The host device will then put the data received the second time into a second slot of its memory (280), and will compute the file length of the second slot (Block 282).

The host device will then compare the file length of the data in Slot No. 2 with the second file length slot (Block 284). If the two file lengths are not equal, the host device will return to that portion of the operational routine where it sends out the second signal to the pen based computer to transfer the data a second time, i.e., Block 268. If the two file lengths are equal, the host device will update the display screen with the message "file compare" next to the slot number of the pen based computer with which it is communicating (Block 286).

The host device will then compare the content of Slot No. 1 with that of Slot No. 2 (Block 288). If the two contents are not the same, the host device will return to that portion of the operational routine where it sends a signal to the pen based computer to transfer the data the first time, i.e., Block 250. If the contents of memory Slot No. 1 and memory Slot No. 2 are the same, the host device will erase the data in memory Slot No. 2 (Block 290), and will update the display so that the message "erase" is displayed next to the slot number of the particular pen based computer with which it is communicating (Block 292), to inform the operator of the system that the data in the second memory slot is being erased.

Because the data has been successfully received by the host device, the host device sends out a signal to the pen based computer to erase the data stored in its memory (Block 294). The pen based computer erases the data in its memory in response to this signal (Block 296).

The data transfer operation, for transferring data from the pen based computer to the host device, has now been completed. The next phase of the operation is to transfer data from the host device to the pen based computers.

As mentioned previously, if there was no data to be transferred from the pen based computer to the host device, that is, the file length decoded by the host device was zero (Block 248), the operational routine skipped the data transfer operation and now returns to the routine at this point, as denoted by reference letter B. The host device determines whether a file exists to send to the particular pen based computer with which it is communicating (Block 298). The host device checks a flag in the look-up table next to the identification/password code stored in the look-up table memory for that particular pen based computer. If no flag exists, which means that no data is to be transferred to the pen based computer, the host device will skip to the discharge/recharge step at the end of the routine. If the check flag does exist for the particular pen based computer with which the host device is communicating, the host device will send a signal to the pen based computer that data is to be sent to the computer (Block 300), and will update the display screen by displaying the message "send No. 1" next to the slot number of the corresponding pen based computer (Block 302).

In response to the signal, the pen based computer gets ready to receive data from the host device; that is, it sets up slots in memory to receive the data (Block 304). The host device then computes the file length of the data to be sent to the pen based computer (Block 306), and sends the data to the pen based computer for a first time (Block 308).

In the same manner that it did when receiving data from the pen based computer, the host device computes the percentage of data being transferred to the pen based computer and provides a "gas gauge" type of segment display, updating the display periodically until all the data is transferred to the pen based computer the first time (shown generally by Block 310).

The pen based computer stores the data in Slot No. 1 of its memory (Block 312), and calculates the file length of the data stored in Slot No. 1 (Block 314).

The host device will then cause the message "send No. 2" to be displayed (Block 316), and sends its data to the pen based computer a second time (Block 318). As it is sending its data to the pen based computer, it again displays a segment gauge of the proportion of data being transferred (Block 320).

The pen based computer stores the data received a second time in Slot No. 2 of its memory (Block 322), and calculates the file length of the data stored in Slot No. 2 (Block 324). The host device will then update the display with the message "remote compare", indicating to the operator of the system that a comparison of the data received both times by the pen based computer is now being made (Block 326). This message is displayed next to each slot number of the pen based computer with which the host device is communicating.

The pen based computer then compares the file length of the data in Slot No. 1 of its memory with the file length of the data in Slot No. 2 (Block 328). If the file length of Slot No. 1 and Slot No. 2 are not equal, the pen based computer will send a signal to the host device indicating that the data has not been properly received (Block 330). The host device will then return to that portion of the operational routine where it will send a signal to the pen based computer that data is to be sent to the computer a first time, that is, Block 302.

If the file lengths of the data in Slot No. 1 and Slot No. 2 are equal, the pen based computer will then compare the contents of Slot No. 1 and Slot No. 2 (Block 332). If the contents of Slot No. 1 and Slot No. 2 are not the same, the pen based computer will send the signal mentioned previously that the data was not received properly (see Block 330), and the host device will resend the data and return to Block 332 in the operational routine.

If the contents of Slot No. 1 equal the contents of Slot No. 2, the pen based computer will send a signal to the host device that the data has been properly received (Block 334). The pen based computer will erase the data stored in the second slot, Slot No. 2 (Block 336), and the host device will send a signal to the pen based computer to disconnect from the host device (Block 338).

The host device will then display next to the slot number of the particular pen based computer with which it is communicating the message "computed" (Block 340), indicating the end of the operational routine. The pen based computer will shut down its power and exit the operational routine (Block 342). The operational routine will then return to Block 206, where the host sends out a polling signal, as denoted by reference letter G. The host device will then activate the charge and discharge circuit 100 in the multiple computer receptacle device (Block 344), which circuit will discharge the batteries of the pen based computers and recharge them to the proper level for future use.

Although the pen based computers and main data gathering and dispatching circuit have been described as including circuitry for carrying out the operation of transferring data between them, as be within the scope of the invention to carry out the operation and to perform the functions performed by the individual circuits shown in FIGS. 5 and 6 by a computer process. In this regard, the system would include a host computer, such as an IBM PC specifically programmed to generate, transmit and receive the various signals described in relation to the embodiments of FIGS. 5 and 6, and having a memory to store data to be outputted by or inputted to the host computer, the multiple computer receptacle device and a series of pen based computers. The pen based computers include a RAM (random access memory) card which may be programmed so that each pen based computer will generate, transmit and receive the signals described with respect to the embodiments shown in FIGS. 5 and 6, and include a memory for storing the incoming and outgoing data described previously. Accordingly, the electrical system of the present invention may function by using a main data gathering and dispatching circuit composed of discrete circuits or a host computer.

An alternative form of the system for transferring data between a host device and a plurality of pen based computers, formed in accordance with the present invention, will now be described with reference to FIGS. 8-11 of the drawings.

FIG. 8 is an alternative construction for the multiple computer receptacle device of the present invention. In the embodiment shown in FIG. 2, the multiple computer receptacle device 4 included a series of divider panels 22. In the construction shown in FIG. 8, the multiple computer receptacle device 4' omits the divider panels, the anti-friction strip members 42 and the L-shaped brackets 40, and now includes a top plate 350 and a bottom plate 352 mounted on the supporting frame 20 situated in the housing 14. Each of the top plate 350 and bottom plate 352 are formed from an anti-friction material, such as Teflon (TM) or Delrin (TM). The exposed surfaces of each of the top and bottom plates facing into the area of the multiple computer receptacle device 4' in which the pen based computers are housed include a series of spaced apart, parallel channels 354 or recesses formed therein. The channels 354 formed in the bottom plate 352 are opposite to and in alignment with corresponding channels 354 formed in the top plate 350 so that the top and bottom plates define a series of parallel slots for receiving pen based computers 12 in the same manner that the divider panels 22 do in the embodiment of the multiple computer receptacle device 4 shown in FIG. 2. The anti-friction material which the top and bottom plates are made of allows the pen based computers to slide easily into their respective slots in the multiple computer receptacle device. As in the previous embodiment, power and data connectors (not shown) are mounted on the inner back wall 26 of the multiple computer receptacle device within the slots defined by the channels of the top and bottom plates 350,352 so as to mate with corresponding connectors mounted on the pen based computers 12.

The multiple computer receptacle device 4' further includes a series of light emitting diodes (LEDs) which are preferably positioned above the computer receiving slots of the multiple computer receptacle device 4' and mounted on the top portion of the front wall 356 of the device. Preferably, there are three different colored LEDs 358,360,362 situated above each slot, although it is envisioned to have a single LED or other indicator which may be controlled to display different colors.

In the preferred form of the multiple computer receptacle device 4', and as shown in FIG. 8 of the drawings, the three spaced apart LEDs above each slot include a red LED 358, a yellow LED 360 and a green LED 362. The LEDs are provided to inform the operator of the condition of the batteries in the pen based computers 12 and whether the data transferring operation is in progress or has been completed.

More specifically, the red LED 358, when lit, indicates that the data transfer operation is in progress. It effectively warns the operator not to remove the unit. When the red LED light 358 is off, this is an indication to the operator that the data transfer operation is over. In another preferred form of the invention, the red LED will flash on and off when the proper identification/password is not received, as will be described in greater detail.

The yellow LED 360 illuminates when the batteries of the pen based computers, mounted in their respective slots in the multiple computer receptacle device, are being discharged or recharged by the charging circuit 100 in the multiple computer receptacle device 4'. The yellow LED 360, when illuminated, thus indicates to the operator that he may remove the pen based computers from the multiple computer receptacle device 4' but that the batteries in the pen based computers may not be fully charged.

The green LED 362 illuminates when the batteries in the pen based computers are fully charged. This is an indication to the operator that the pen based computers may be removed and that they are fully charged and ready for use. The interconnection of the LEDs 358-362 to the circuitry used in the data transferring system of the present invention will be explained in greater detail.

In the previous embodiments described with respect to FIGS. 1-7, the system of the present invention included a host device or main data gathering and dispatching circuit which was at a remote location and separated from the multiple computer receptacle device and interconnected by a series of data cables. In the embodiment described with respect to FIGS. 8-11, it is envisioned that the host device or main data gathering and dispatching circuit may be incorporated into the multiple computer receptacle device 4'.

As illustrated by FIG. 8 of the drawings, the main data gathering and dispatching circuit 2 is mounted by sliding brackets 364 in the rear of the housing of the multiple computer receptacle device 4' and preferably below (although it is shown above) the printed circuit board containing the circuitry for the charge and discharge circuit 100. As will be explained in greater detail, the main data gathering and dispatching circuit 2 can interface with various other units and a dispatching work station, as shown in FIG. 10.

The main data gathering and dispatching circuit 2 which is mounted in the multiple computer receptacle device 4' includes a number of components, as shown in block diagram form in FIG. 9. Basically, the circuit includes a processor 366 with preferably a one megabyte memory, which acts as a central processing unit (CPU). Part No. 80386 manufactured by Motorola Semiconductor Company is suitable for use as the processor.

Connected to the processor 366 is a random access memory (RAM) board 368 preferably having about 8 to about 10 megabytes of memory for command processing. The RAM board is where the data to be transferred from the pen based computers to the main data gathering and dispatching circuit, and visa versa, is stored. A suitable RAM board 368 (which includes Part No. 80386 mentioned above) for use in the present invention is Part No. PCA6130 manufactured by American Advantech Corp.

The main data gathering and dispatching circuit 2 further includes a read only memory (ROM) board 370. The ROM board 370 is connected to the processor 366, and stores the operational and communication software for operating the data transferring system of the present invention. A suitable ROM board for use in the present invention is Part No. PCD890 manufactured by American Advantech Corp.

Also included in the main data gathering and dispatching circuit is a multiport communication board 372. The multiport communication board 372 is connected to the processor 366, and is further connected to the pen based computers 12 by a series of data bus cables 373, which cables are interconnected to the data connectors 28 mounted on the inner rear panel 26 of the multiple computer receptacle device. A suitable multiport communication board for use in the present invention is Part No. PC/8 manufactured by Digiboard Inc.

A signal input/output (I/O) board 374 is also included. The signal input/output board 374 is connected between the processor 366, and the charging circuit 100 and the red LEDs 358. The red LED 358 is controlled at least in part by the signal I/O board, and the yellow and green LEDs 360,362 are controlled by the charging circuit, as will be described. A suitable signal I/O board 374 for use in the main data gathering and dispatching circuit of the present invention is Part No. P10-96 manufactured by Keithley Metrabyte Inc.

The main data gathering and dispatching circuit further includes a network adaptor 376. The network adaptor is connected to the processor 366, and is adapted to be connected to a network server or a multiple access unit, as will be described, by a single cable. The network adaptor 376 may be Part No. P1347 manufactured by Proteon Inc.

Optionally, the main data gathering and dispatching circuit may include a RAM card write device 378. The RAM card write device 378 is connected to the processor 366 and is adapted to receive a RAM card 379. The RAM card write device may be mounted on a side wall or on a rear wall of the multiple computer receptacle device, and include a slot for receiving the RAM card.

The RAM card 379, of course, contains a memory which is adapted to store the security identification codes, i.e., the password codes for access to the system which, in the embodiment of FIGS. 1-7, are stored in the memory of the host device. A suitable RAM card write device 378 for use in the main data gathering and dispatching circuit of the present invention is Part No. TCB101-02 manufactured by Databook Inc.

The main data gathering and dispatching circuit 4' in the embodiment of FIG. 9 interfaces with a number of units of the system, as illustrated by FIG. 10. It is envisioned that the system for transferring data includes a number of remotely located dispatching work stations 380 which are diskless. Data to be transferred to the pen based computers may be inputted to the main data gathering and dispatching circuit by the dispatching work stations 380. This data is stored in the RAM board 368 of the main data gathering and dispatching circuit and transferred to the pen based computers 12 during the transfer operation.

The system may further include a network file server 382, which stores data received from the main data gathering and dispatching circuit (which data was previously received from the pen based computers) and can be accessed by the operator to manipulate the data.

Additional multiple computer receptacle devices, such as a two tiered device 384 (having preferably 16 slots for receiving pen based computers) and a four tiered multiple computer receptacle device 385 (having preferably 32 computer receiving slots) may also be interconnected to the dispatching work stations 380 and the network file server 382. Each of the multiple computer receptacle devices communicates with the network file server and the dispatching work stations through a multiple access unit (MAU) 386. The MAU 386 interconnects to the network adaptor 376 of each main data gathering and dispatching circuit mounted in the multiple computer receptacle devices by a single bus cable. A suitable MAU for use in the present invention is Part No. P2700 manufactured by Proteon Inc.

The operation of the main data gathering and dispatching circuit 4' of the embodiment shown in FIG. 9 is very similar to the operation of the host device or main data gathering and dispatching circuit shown in the embodiments of FIGS. 1-7. A flow chart of the operation of the system is illustrated by FIGS. 11a-11h. The functional blocks which are common to the flow charts of FIGS. 7a-7h are indicated with the same reference number. The basic difference between the two operations is that in the latter embodiment, the host device or main data gathering and dispatching circuit does not include a cathode ray tube (CRT) display of the operation of the system, and only the various colored LEDs 358-362 are used for advising the operator of the conditions of the system. Accordingly, Blocks 208, 218, 236, 252, 258, 260, 270, 276, 278, 286, 292, 302, 310, 316, 320, 326 and 340, which relate to updating the display screen, have been eliminated from the operational flow chart shown in FIG. 11. The other differences in the operation of the system shown in FIG. 11 will now be described.

When the first signal (indicating that the pen based computer is loaded into the receptacle device) is properly received (Block 204), the red LED 358 is illuminated (Block 402). As mentioned previously, the red LED 358 indicates that the data transferring operation is under way. The term "host" referred to in the operational flow chart corresponds to the main data gathering and dispatching circuit of the present invention, and the term "pen" refers to the various pen based computers 12 mounted in the slots of the multiple computer receptacle device.

After the data contained in memory slot no. 1 is compared to the data in memory slot no. 2 (Block 288) during the transfer of data from the pen based computers to the host device or main data gathering and dispatching circuit, the data in the main data gathering and dispatching circuit, and in particular in the RAM board memory, is transferred to the network data server (Block 404).

In the transfer of data from the main data gathering and dispatching circuit to the pen based computers, the main data gathering and dispatching circuit asks the network file server 382 whether a file exists to send to the pen based computer with which the main data gathering and dispatching circuit is communicating (Block 298). If a file does exist, then the data is transferred from the data server to the main data gathering and dispatching circuit and temporarily stored in the memory of the RAM board 368 of the circuit (Block 406). Operation then continues in the manner described previously with respect to the embodiments of FIGS. 1-7.

At the end of the data transferring operation, and after the pen based computer is shut down and exits the transfer program (Block 342), the main data gathering and dispatching circuit turns off the red LED (Block 408) to indicate that the data transferring operation has been completed, and the charge and discharge circuit 100 is then activated (Block 344).

In an alternative form of the invention, the host device may be activated to continuously poll the slots of the receptacle device (Block 206) without the first signal being generated (Block 200). If no pen based computer is mounted in the corresponding slot of the receptacle device, the host device will not receive a return signal and will continue to send out a polling signal. At the end of the data transfer operation, when the pen based computer is removed from the receptacle device, the host device will continue to poll that slot for another pen based computer.

Certain pen based computers 12, such as those manufactured by Grid Systems mentioned previously, include an internal diode which is coupled to the nickel-cadmium (Ni-cad) battery pack, which diode will prevent the Ni-cad batteries from discharging through an external circuit. Accordingly, it may be difficult for the charge and discharge circuit of the present invention to discharge such pen based computer models having a "discharge blocking" diode while the Ni-cad batter pack remains mounted in the pen based computer.

For this reason, and for other reasons, it may be desirable to include a separate battery pack charging rack 450, constructed in accordance with the present invention for this purpose. One form of a battery pack charging rack is illustrated by FIG. 12 of the drawings.

The battery pack charging rack 450 is similar in construction in many respects to the multiple computer receptacle device 4. The battery pack discharge rack includes a housing 452 having a plurality of parallel, spaced apart divider panels 454, adjacent divider panels defining slots 456. Each slot is dimensioned to receive a respective battery pack 458 of a pen based computer.

An inner rear panel 455 is mounted perpendicularly to the rear edges of the divider panels 454, and has mounted on it a plurality of connectors 451 or contacts which are positioned between the divider panels and within the slots 456 so that they make an electrical connection with corresponding contacts of the battery packs mounted in the receiving slots, in much the same way as the pen based computers 12 are mounted in the slots 24 and make contact with the connectors of the multiple computer receptacle device 4.

The battery pack charging rack 450 also includes a outer rear panel 457, which is spaced apart from the inner rear panel to define a space in which circuitry, which will be described in greater detail, which interfaces with the battery packs mounted in the receiving slots 456 and with the multiple computer receptacle device, is situated.

Once the battery pack 458 is removed from the pen based computer and mounted in the battery pack charging rack 450, it may be freely discharged, as the discharge blocking diode remains in and is part of the circuitry of the pen based computer. The battery pack charging rack is coupled to the multiple computer receptacle device 4 and the charge and discharge circuit 100 mounted in the multiple computer receptacle device by a multi-wire cable.

FIG. 13 illustrates, in block diagram form, one form of the charge and discharge circuit 100 of the present invention. Basically, and as mentioned previously, the charge and discharge circuit includes a transformer and rectifier circuit 460, which provides an unregulated voltage of about 20 to about 25 volts. A regulator is also included, and will be discussed in greater detail, for providing regulated voltage to the various integrated circuits used in the charge and discharge circuit.

The charge and discharge circuit 100 further includes a constant current circuit 462, which provides a constant and regulated current to the battery module or pack 458 of the pen based computers.

The charge and discharge circuit further includes voltage sensing circuits 464 which are coupled to the battery module of the pen based computer, a high current discharge circuit 466, which is also coupled to the battery module to discharge the battery of the pen based computer, and a logic and control circuit 468 which is responsive to an external signal on a data bus from the main data gathering and discharge circuit or host device 2, or, alternatively, from the push-button switch 51 (or first signal generator 50) mounted on the multiple computer receptacle device 4. The logic and control circuitry 468 controls the high current discharge circuit 466 as well as the constant current circuit 462. The front panel indicators, (generally designated by reference number 469 in FIG. 13) on the multiple computer receptacle device, that is, the red, yellow and green LEDs 458-462, are also controlled by the logic and control circuit, and are provided with voltages from the transformer and rectifier circuit 460.

The transformer and rectifier circuit 460 is used in common for all of the pen based computers. However, each of the constant current circuit 462, voltage sensing circuits 464, logic and control circuit 468 and the high current discharge circuit 466 of the charge and discharge circuit, as well as a red, yellow and green front panel indicator, are duplicated for each pen based computer of the data transfer system. In other words, if the multiple computer receptacle device 4 is fashioned to accept eight pen based computers, then the charge and discharge circuit 100 will include one transformer and rectifier circuit 460 and eight high current discharge circuits 466, eight voltage sensing circuits 464, eight logic and control circuits 468 and eight constant current circuits 468. Thus, there will be eight data buses from the main data gathering and discharge circuit 2, each data bus controlling a respective logic and control circuit 468 corresponding to one of the pen based computers.

One form of a charge and discharge circuit 100 formed in accordance with the present invention is shown schematically in FIGS. 14A-14D. The actual values and part numbers of the components used in the electronic circuitry shown in FIGS. 14A-14D are for illustrative purposes only and to facilitate an understanding of the invention. However, alternative components, and values for these components, may be substituted by one skilled in the art to provide the same or similar results. The numbers positioned adjacent to the integrated circuits shown in FIGS. 14A-14D represent the pin numbers of the circuits.

The circuit includes a step-down transformer T1, having a center tapped secondary winding, which is connected to a pair of diodes CR1, CR2 to provide full wave rectification. A capacitor C1 is used for filtering. The transformer voltage provides an unregulated voltage of between 20 and 25 volts. The unregulated voltage is provided to a regulator VR1 whose output provides a regulated +15 volts.

The circuit described so far is only repeated once for all of the pen based computers or battery packs of the computers which are powered by the charge and discharge circuit. The remainder of the circuit to be described is repeated for each of the pen based computers received by the multiple computer receptacle device and powered by the charge and discharge circuit.

The charge and discharge circuit 100 includes a constant current circuit 462 for charging the battery pack of a respective pen based computer. The constant current circuit 462 is formed from the combination of transistor Q101, transistor Q102, switch transistor Q103, green LED diode CR101 and series resistor R101. The constant current source is controlled by a first voltage comparator U101B.

More specifically, the inverting input of comparator U101B is connected to the positive side of the pen based computer battery. The negative side is grounded. When the battery of the pen based computer is fully charged, its voltage will be approximately 17 volts. Accordingly, comparator U101B will sense when the voltage falls below 17 volts. The non-inverting input of comparator U101B is connected to a 17 volt zener diode CR105 which is biased on through resistor R113 connected to the +20 volt supply voltage. If, for instance, the voltage on the battery falls to 16 volts, the output of comparator of U101B (which is preferably an open-collector output) will be at a high logic level, pulled up by the +15 volt regulated voltage through pull-up resistor R109. Through resistor R109 and base resistor R110, switch transistor Q103 will be turned on. Transistor Q103 has its collector connected to the base of transistor Q102 through resistor R103 and, when transistor Q103 is turned on, transistor Q102 will be forward biased which, in turn, will turn on transistor Q101 which is connected in a common base configuration with its base connected to the collector of transistor Q102 through resistor R102.

LE CR101 is connected between the base of transistor Q101 and the positive side of the pen based computer battery, and emitter resistor R101 is connected between the emitter of transistor Q101 and the positive side of the battery. LED CR101 provides a 2 volt reference voltage, and also provides an internal indication, for test purposes, of whether the constant current source is operating properly. Assuming that the base-emitter voltage drop of transistor Q101 is 0.7 volts, and that the voltage drop across LED CR101 is 2 volts, then 1.3 volts will be dropped across resistor R101. The value of resistor R101 is chosen to allow a certain amount of current to flow from the constant current source to the battery. If, for example, resistor R101 is chosen to have a value of 10 ohms, then the current flowing from the constant current source is 130 milliamps.

130 milliamps is chosen to be the preferred current for charging the battery. 30 milliamps will be used for running the circuit of the pen based computer during the data transfer operation, and 100 milliamps is, for certain pen based computer models such as those manufactured by Grid Systems Corporation, the recommended maximum charging current for the battery pack used in the computer. Accordingly, when the pen based computers are mounted in the multiple computer receptacle device, the constant current source of the charge and discharge circuit will not only power the unit but also charge the batteries during the data transfer operation and after the operation has been completed.

When the pen based computer battery has been charged to over 17 volts, the output of comparator U101B will go to a low logic level, cutting off switch transistor Q103. This, in turn, will cut off transistor Q102 and transistor Q101, so that current will no longer be provided by the constant current source to the battery. When the voltage on the battery falls slightly below the 17 volt level, comparator U101B will pulse the constant current source on again until the battery voltage again rises to greater than 17 volts. This pulsing or "burbing" of current to the battery will maintain the battery in a fully charged condition.

The charge and discharge circuit is preferably controlled by the main data gathering and dispatching circuit or host device 2 of the present invention. For this purpose, a data bus is provided to the charge and discharge circuit from the main data gathering and dispatching circuit. A signal from the main data gathering and dispatching circuit is provided to each of the logic and control circuits 468 of the charge and discharge circuit for each pen based computer which is mountable in the multiple computer receptacle device 4.

Two time-separated pulses on the bus input control the operation of the charge and discharge circuit. The first pulse is provided through a pair of series connected NAND gates U105A and U105B, configured as inverters and having pull-up resistors R129 and R130, which gates are provided for making the TTL bus input compatible with the CMOS logic preferably used in the circuit, to the inputs of NAND gate U103B configured as an inverter, whose output is provided to the Set input of RS flip-flop U102B. The Q output of flip-flop U102B was, previous to the first pulse, at a low logic level, which level is provided to one input of NAND gate U103A through resistor R117, thereby blocking the first pulse from passing through NAND gate U103A (the output of gate U103A will be at a high logic level).

When flip-flop U102B is set, the Q output will go to a high logic level. This level will be delayed in being provided to the input of gate U103A by passing through the delaying circuit comprising resistor R117 and capacitor C101. Either the pulse width of the first pulse on the bus input or the time constant of the delaying circuit is selected such that the first pulse has ended before the input to gate U103A has gone to a high logic level, enabling the gate.

The Q output of flip-flop U102B is connected to the base of transistor Q109 through base resistor R116. With a high logic level on the Q output of flip-flop U102B, transistor Q109 is turned on to allow current to flow from the 15 volt regulated supply through series resistor R122 and through red LED FP LED (i.e., front panel LED1). LED FP LED1 is the red LED indicator 358 mounted on the front panel above the corresponding pen based computer receiving slot on the multiple computer receptacle device which was discussed previously, and is connected to the circuit through connector pins J103-1 and J103-6. The red LED is illuminated when a data transfer operation is underway.

As mentioned previously, in a preferred form of the invention, the red LED 358 will flash on and off when the proper identification/password is not received. For this purpose, integrated circuit U104 is provided. Circuit U104 is a conventional 555 timer configured for a stable operation and whose output (Pin 3) is connected to the base of transistor Q109 through resistor R126. The threshold and discharge inputs (Pins 6 and 7) of timer U104 are connected to the resistors R127 and R128 and capacitor C102, all of which are connected in series, which determine the periodicity of the timer's output signal. Diode CR106 is connected in parallel with resistor R128 and is included to provide the output signal with a 50% duty cycle.

An ERROR DATA IN signal from the host device is provided to the Set input of flip flop U102D through a NAND gate U105C configured as an inverter and having a pull-up resistor R131. When an invalid identification code or password is received by the host device from the pen based computer, a high logic level pulse is received on the ERROR DATA IN input, which sets flip-flop U102D so that its Q output goes to a high logic level. The Q output is connected to the Reset input (Pin 4) of timer U104. When the Q output is at a high logic level, timer U104 is enabled. The positive pulses on the timer's output will turn transistor Q109 on, causing the red LED 358 (FP LED1) situated above the pen based computer which is sending the invalid code to flash.

The output of gate U103B is connected to the Reset input of flip flop U102D. Thus, when the first pulse is received on the bus input, signifying the beginning of the data dump operation, flip-flop U102D will be reset.

When the data transfer operation has been completed, a second pulse is provided to the bus input of the charge and discharge circuit corresponding to a particular pen based computer. The second pulse is provided to the other input of NAND gate U103A, which had been previously enabled when flip-flop U102B was set, which provides a low logic level on the output of the gate. The output of gate U103A is provided to the Reset input of flip-flop U102B through resistor R125, which causes the Q output of flip-flop U102B to go to a low logic level. The low logic level cuts off transistor Q109 and shuts off the red LED FP LED1, indicating that the data transfer operation for this particular pen based computer has been completed. The output of gate U103A is also provided to the Set input of flip-flop U102A, whose Q output goes to a high logic level. The Q output controls the high current discharge circuit 466 of the charge and discharge circuit 100.

More specifically the Q output of flip-flop U102A is provided to the base of transistor Q108. The high logic level turns on transistor Q108, whose collector is connected to +15 volts through resistor R107. Transistor Q104 has its base connected to the collector of transistor Q108 through base resistor R111 and thus is controlled by transistor Q108. When transistor Q108 turns on, transistor Q104 turns off. The collector of transistor Q104 is connected to the +20 volt supply through resistor R105 and to the cathode of a 5 volt zener diode CR102. The anode of diode CR102 is connected to the base of transistor Q105 and to a yellow LED CR104. The collector of transistor Q105 is connected to the positive terminal of the pen based computer battery, and its emitter is connected to ground through emitter resistor R112. The cathode of LED CR104 and the emitter of transistor Q104 are also connected to ground.

As can be seen from the above description and as shown in FIG. 14A, the high current discharge circuit 466 is very similar in structure to the constant current circuit 462 supplying current to the battery. When flip-flop U102A is set, transistor Q108 is turned on which, in turn, turns off transistor Q104. This forward biases transistor Q105 so that current will be quickly drawn from the battery of the pen based computer through transistor Q105 and through emitter resistor R112 to ground. LED CR104 sets up a 2 volt reference voltage between the base of transistor Q105 and ground. Assuming that there is a 0.7 volt base-emitter voltage drop across transistor Q105, then the voltage across resistor R112 will be 1.3 volts. The value of resistor R112 is selected to allow a particular constant current to be drawn from the battery through transistor Q105. If resistor R112 is selected to be 1 ohm, then current will be drawn from the battery (and also from the constant current circuit which remains on) at a constant rate of 1.3 amps, quickly discharging the battery to a particular level.

A second voltage sensing circuit senses the voltage on the battery of the pen based computer. This second voltage sensing circuit includes comparator U101A. The non-inverting input of comparator U101A is coupled to the positive terminal of the battery of the pen based computer. The inverting input is connected to a resistor divider network comprised of resistor R106 and resistor R108. The values of resistors R106 and R108 are selected to provide a 10 volt level on the inverting input of comparator U101A.

When the voltage on the battery is above 10 volts, the output of comparator U101A will be at a high logic level. When the voltage on the battery falls to below a 10 volt level, the output of comparator U101A will go to a low logic level.

The output of comparator U101A, which is connected to resistor R104 to +15 volts and to capacitor C103 to ground, is provided to the Reset input of flip-flop U102A. The low logic level will reset flip-flop U102A so that its Q output will go to a low logic level. The low logic level on the Q output will cut off transistor Q108 which, in turn, will turn on transistor Q104. As a result, transistor Q105 will be cut off so that no more current is drained through transistor Q105 from the battery of the pen based computer. Since no current is being drawn from the battery of the pen based computer, it will now begin to recharge due to the current provided to it by the constant current circuit 462.

As mentioned previously, the second pulse received on the bus input will pass through NAND gate U103A. The output of gate U103A is provided to the reset input of flip-flop U102C, Which input is also connected to capacitor C104 to ground. The low level on the output of gate U103A will ensure that flip-flop U102C is reset and that its Q output is at a low logic level. The Q output of flip-flop U102C is connected to the base of transistor Q106 through base resistor R124. The emitter of transistor Q106 is connected to the collector of transistor Q110, and the collector transistor Q106 is connected to LED FP LED3 (i.e., front panel LED3) through connectors J103-3,8, which is the green LED 362 which, when illuminated, indicates that the battery of the pen based computer has been completely recharged. LED FP LED3 is connected to +15 volts through a series resistor R114. The base of transistor Q110 is connected through resistor R121 to the anode of red LED FP LED1, and the emitter is grounded.

When the battery has been recharged so that its voltage is greater than 17 volts, the output of comparator U101B goes to a low logic level, which sets flip-flop U102C. The Q output of flip-flop U102C goes to a high level and turns on transistor Q106. If the red LED FP LED1 is off, the voltage provided to the base of transistor Q110 will be high enough to turn on transistor Q110 so that current is conducted through LED FP LED3 to illuminate the LED.

As mentioned previously, a third LED 360, which is preferably yellow, is also mounted on the front panel of the multiple computer receptacle device 4. The yellow LED, when illuminated, indicates that the data transfer operation is completed but that the battery of the pen based computer may not be in a fully charged state. For this purpose, LED FP LED2 is provided. LED FP LED2 is connected through connector J103-7,2 to +15 volts through a series resistor R120 and to the collector of transistor Q107, whose emitter is connected to ground. The base of transistor Q107 is connected to the output of a NAND gate U103D, functioning as an inverter, through a base resistor R119. The inputs of NAND gate U103D are connected together and to the output of NAND gate U103C having one input which is connected to the anode of green LED FP LED3 and having its other input connected to the anode of red LED FP LED1. Connected in this manner, the yellow front panel LED 360 will only light when both the red LED 358 and the green LED 362 are off.

In another preferred form of the invention, the multiple computer receptical device may include a plurality of switches SW101, one switch for each pen based computer charging circuit. The switches SW101 are preferably mounted on the front panel of the receptacle device above or below each receiving slot. As shown in FIG. 14A, the switch SW101 is a single pole, single throw push button switch. One pole is grounded, and the other pole is connected to the reset inputs of flip-flops U102B and U102C and the set input of U102A. Switch SW101 is provided when it is desired to use the multiple computer receptacle device to just charge the batteries of the pen based computers received in the slots while bypassing the data dump operation. When switch SW101 is pressed, flip-flops U102B and U102C are reset and flip-flop U102A is set. This will energize the high current discharge circuit, and the circuit 100 shown in FIG. 14A will discharge and recharge the battery of the respective pen based computer as if the data dump operation has been completed.

Also shown in FIGS. 14A-14C is power supply circuit including a 5.1 volt zener diode CR106 coupled between ground and one end of resistor R132, whose other end is connected to +15 volts, and a capacitor C105 connected in parallel with diode CR106. The power supply circuit provides a +5 volt supply to those integrated circuits requiring this voltage.

The positive and negative (ground) outputs of the charge and discharge circuit 100 for each pen based computer are provided on connectors P101-1 and P101-2, respectively. If no battery pack charging rack 450 is included in the system, then the eight pair of connectors P101-1 and P101-2 are connected to respective power connectors of the multiple computer receptacle device.

If the battery pack charging rack 450 is to be incorporated in the system, then preferably the positive and ground outputs of the charge and discharge circuit 100 are provided on connector P101-1 and P101-2, respectively, which mates with corresponding connector J101-1 and J101-2, respectively, of the battery pack charging rack 450, as shown in FIG. 14D, which connectors are repeated for each of the batteries capable of being received by the battery pack charging rack. The positive voltage is connected to the wiper of a relay K1, which switches between two relay contacts, one contact X being provided to the positive terminal or contact of the connector J102-1 which mates with the battery pack received by the battery pack charging rack, and the other contact Y being returned to the multiple computer receptacle device 4 through an appropriate cable and provided to the positive terminal of the power connector 30 mounted on the inner rear panel of the multiple computer receptacle device for that respective pen based computer.

As mentioned above, the battery pack charging rack 450 includes a plurality of relays K1, one relay associated with each battery pack capable of being received by the charging rack. One terminal of the relay's coil is connected to the collector of a transistor TIP31, and the other terminal is connected to the wiper of a single pole, single or double throw switch S1, as will be described. The base of the transistor TIP31 is connected through a base resistor R11 to a data line provided to the battery pack charging rack from the main data gathering and dispatching circuit or host device.

The main data gathering and dispatching circuit may provide a REMOTE signal on the data line to transistor TIP31 situated in the battery pack charging rack. Transistor TIP31 has its emitter grounded. The remote signal will turn on transistor TIP31. One pole of switch S1 is connected to a +20 volt source, and the wiper of switch S1 is connected to the other terminal of the coil of relay K1. When transistor TIP31 is turned on by the remote signal, the relay coil is energized, causing the current provided on J101-1 from the constant current circuit 462 to be provided to the battery pack situated in the battery pack charging rack 450. If no remote signal is provided, transistor TIP31 is cut off so that no current flows through the coil of relay K1. Under such circumstances, the constant current provided on connector J101-1 will be returned through the relay contacts to the battery pack which remains in the pen based computer situated in the receiving slots of the multiple computer receptacle device 4.

As mentioned previously, a plurality of switches S1 may be provided, one switch S1 for each receiving slot of the battery pack charging rack 450. Switch S1 is, effectively, an override switch so that if a remote signal is provided by the main data gathering and dispatching circuit, the connection between relay K1 and the +20 volt source may be broken so that current is routed through the contacts of the relay back to the battery pack remaining in the pen based computer.

Alternatively, an additional switch S2 may be provided for each receiving slot of the battery pack charging rack. Switch S2 is a single pole, single throw switch which is positioned between ground and the collector of transistor TIP31. Accordingly, if no remote signal is received by the main data gathering and dispatching circuit, switch S2 may be activated while switch S1 is in the proper position to provide power to the coil of relay K1 to energize relay K1 and to cause current from the constant current circuit to flow into the battery pack removed from the pen based computer and situated in a respective receiving slot of the battery pack charging rack 450. Although not shown in FIG. 12 switches S1 and S2 may be mounted on the front panel of the battery pack charging rack 450 above and below their respective slots.

The multiple computer receptacle device conveniently allows a plurality of pen based computers to "dump" or transmit data inputted to the pen based computers to a host computer or main data gathering and dispatching circuit concurrently and automatically. The system of the present invention provides a multiple connection between the host computer and the plurality of pen based computers. The operator need not connect one pen based computer to the host computer at a time to dump data from the pen based computer, disconnect the pen based computer and reconnect another pen based computer, in a time consuming process.

Also, the present invention automatically tends to housekeeping functions, such as discharging and recharging the battery packs of the pen based computers. This is automatically done after the data has been transferred from the pen based computers to the host computer.

The present invention also has the capability of transferring data from the host computer concurrently to a plurality of pen based computers loaded into the multiple computer receptacle device, rather than the time consuming process of transferring data from the host computer to each pen based computer individually.

The operator need not be present for the data transfer operation--the present invention will transfer the data automatically. Also, the operator need not be a trained technician. The users of the pen based computers merely have to slide the pen based computers into the multiple computer receptacle device and, when all of the pen based computers are loaded, press the start switch (i.e., the first signal generator 102) on the multiple computer receptacle device. The present invention will take over the operation after that point.

The multiple computer receptacle device may also include a timer 180 connected to the first signal generating circuit such that the data transfer operation and battery pack recharge operation may be automatically performed at a predetermined time, such as after regular business hours.

Although illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various other changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention. 

What is claimed is:
 1. In combination:a plurality of pen based computers, each pen based computer including a battery, a display and an unlighted pen for handwritten input of information on the display; and apparatus for transferring data from the plurality of pen based computers, which comprises: a housing; a support frame mounted in the housing, the support frame being adapted to support a plurality of pen based computers, the support frame including a plurality of spaced apart parallel divider panels, adjacent divider panels defining between them a slot for receiving a respective pen based computer, the support frame further including a first back panel, the first back panel being mounted on the divider panels and being disposed transversely thereto; a plurality of guide brackets, each of the guide brackets being mounted on the support frame and disposed within a respective slot defined by adjacent divider panels, the guide brackets directly engaging an edge of the pen based computers to facilitate insertion of the pen based computers into respective receiving slots; a plurality of data input/output connectors, the data connectors being mounted on the first back panel and positioned between adjacent divider panels so as to be adapted to mate with corresponding data connectors mounted on the pen based computers; a plurality of power connectors, the power connectors being mounted on the first back panel and positioned between adjacent divider panels so as to be adapted to mate with corresponding power connectors mounted on the pen based computers; circuit means coupled to the plurality of data input/output connectors for automatically transmitting data concurrently to the plurality of pen based computers for storage of the data therein and for automatically receiving data concurrently from the plurality of pen based computers; and means coupled to the power connectors for discharging and recharging the batteries of the pen based computers.
 2. A combination as defined by claim 1, wherein the guide brackets are formed from an anti-friction material.
 3. A combination as defined by claim 2, wherein the guide brackets are formed from a Teflon (TM) material.
 4. A combination as defined y claim 1, wherein the apparatus for transferring data further comprises:a plurality of anti-friction strip members, the anti-friction strip members being mounted on the divider panels, the anti-friction strip members having an exposed surface within the pen based computer receiving slots for engagement with the pen based computers situated in the slots.
 5. An electrical system for transferring data signals concurrently between a host device and a plurality of pen based portable computers, each of the plurality of pen based computers including a battery, a display and an unlighted pen for handwritten input of information on the display, at least one of the pen based computers being received by a multiple computer receptacle device, the electrical system comprising:a first signal generating circuit, the first signal generating circuit forming a portion of the multiple computer receptacle device and providing a first signal indicative of the at least one pen based computer received by the multiple computer receptacle device; a first signal receiving circuit, the first signal receiving circuit forming a portion of the host device and providing an output signal in response to the first signal; a second signal generating circuit, the second signal generating circuit forming a portion of the host device and providing a second signal for polling the pen based computers and for performing a security check with respect thereto; a second signal receiving circuit, the second signal receiving circuit forming a portion of the at least one pen based computer and generating an output signal in response to the second signal; a third signal generating circuit, the third signal generating circuit forming a portion of the at least one pen based computer and providing a third signal for polling the host device and for performing a security check with respect thereto; a third signal receiving circuit, the third signal receiving circuit forming a portion of the host device and generating at least first and second output signals in response to the third signal; a first look-up table memory circuit, the first look-up table memory circuit forming a portion of the host device and having stored therein logic data corresponding to a plurality of first identification/password logic codes, each of the first identification/password codes corresponding to a respective pen based computer; a fourth signal generating circuit, the fourth signal generating circuit forming a portion of the host device and providing a fourth signal corresponding to at least one of the first identification/password codes; a second look-up table memory circuit, the second look-up table memory circuit forming a portion of the at least one pen based computer and having stored therein logic data corresponding to a second identification/password logic code; a fourth signal receiving and comparator circuit, the fourth signal receiving and comparator circuit forming a portion of the at least one pen based computer and providing an output signal in response to the fourth signal, the PG,74 second look-up table memory circuit being electrically coupled to the fourth signal receiving and comparator circuit, the fourth signal receiving and comparator circuit comparing the second identification/password code logic data stored in the second look-up table memory circuit with logic data corresponding to the fourth signal, and providing an output signal in response to the comparison thereof; a fifth signal generating circuit, the fifth signal generating circuit forming a portion of the at least one pen based computer and providing a fifth signal in response to the output signal of the fourth signal receiving and comparator circuit, the fifth signal corresponding to the second identification/password code logic data stored in the second look-up table memory circuit of the at least one pen based computer; a fifth signal receiving and comparator circuit, the fifth signal receiving and comparator circuit forming a portion of the host device and comparing the first identification/password code logic data stored in the first look-up table memory circuit with logic data corresponding to the fifth signal, and providing an output signal in response thereto, the output signal being provided to the second signal generating circuit, the second signal generating circuit being responsive to the output signal and providing the second signal in response thereto; an identification/password code selection circuit, the identification/password code selection circuit forming a portion of the host device and being electrically coupled to the first look-up table memory circuit, the identification/password code selection circuit generating third identification/password codes for storage by the first look-up table memory circuit and for substitution in the first look-up table memory circuit of the first identification/password signals; a sixth signal generating circuit, the sixth signal generating circuit forming a portion of the host device and providing a sixth signal corresponding to the third identification/password code generated by the identification/password code selection circuit; a sixth signal receiving circuit, the sixth signal receiving circuit forming a portion of the at least one pen based computer and providing an output signal in response thereto, the output signal corresponding to the third identification/password code and being provided to the second look-up table memory circuit, the second look-up table memory circuit storing the output signal corresponding to the third identification/password code as logic data in substitution for the second identification/password code logic data; a first data memory circuit, the first data memory circuit forming a portion of the at least one pen based computer and having stored therein logic data inputted to the pen based computer by the user thereof; a first data transmission circuit, the first data transmission circuit forming a portion of the at least one pen based computer and electrically coupled to the first data memory circuit for transmitting first data signals corresponding to the logic data stored in the first data memory circuit, the first data signals being transmitted by the first data transmission circuit a first time and a second time; a first data receiving circuit, the first data receiving circuit forming a portion of the host device and receiving the first data signals; a first data buffer memory circuit, the first data buffer memory circuit forming a portion of the host device and coupled to the first data receiving circuit and storing therein the first data signals transmitted the first time as first pen based computer transmitted logic data, and storing therein the first data signals transmitted the second time as second pen based computer transmitted logic data; a first file length and content check circuit, the first file length and content check circuit forming a portion of the host device and electrically coupled to the first data buffer memory circuit, the first file length and content check circuit comparing the first pen based computer transmitted logic data with the second pen based computer transmitted logic data and providing an output signal in response to the comparison thereof; a seventh signal generating circuit, the seventh signal generating circuit forming a portion of the host device and providing a seventh signal in response to the output signal of the first file length and content check circuit; a seventh signal receiving circuit, the seventh signal receiving circuit forming a portion of the at least one pen based computer and providing an output signal in response to the seventh signal, the output signal being provided to the first data memory circuit, the first data memory circuit erasing the logic data stored therein in response to the output signal of the seventh signal receiving circuit; a second data memory circuit, the second data memory circuit forming a portion of the host device and having stored therein logic data inputted to the host device by the operator thereof; a second data transmission circuit, the second data transmission circuit forming a portion of the host device and electrically coupled to the second data memory circuit for transmitting second data signals corresponding to the logic data stored in the second data memory circuit, the second data signals being transmitted by the second data transmission circuit a first time and a second time; a second data receiving circuit, the second data receiving circuit forming a portion of the at least one pen based computer and receiving the second data signals; a second data buffer memory circuit, the second data buffer memory circuit forming a portion of the at least one pen based computer and coupled to the second data receiving circuit and storing therein the second data signals transmitted the first time as first host device transmitted logic data and storing therein the second data signals transmitted the second time as second host device transmitted logic data; a second file length and content check circuit, the second file length and content check circuit forming a portion of the at least one pen based computer and electrically coupled to the second data buffer memory circuit, the second file length and content check circuit comparing the first host computer transmitted logic data with the second host computer transmitted logic data and providing an output signal in response to the comparison thereof; an eighth signal generating circuit, the eighth signal generating circuit forming a portion of the at least one pen based computer and providing an output signal in response to the output signal of the second file length and content check circuit; an eighth signal receiving circuit, the eighth signal receiving circuit forming a portion of the host device and providing an output signal in response to the eighth signal; a ninth signal generating circuit, the ninth signal generating circuit forming a portion of the host device and providing a ninth signal in response to the output signal of the eighth signal receiving circuit; a ninth signal receiving circuit, the ninth signal receiving circuit forming a portion of the at least one pen based computer and providing a disable signal in response to the ninth signal, the disable signal being provided to the second signal receiving circuit, the second signal receiving circuit being responsive thereto; a keyboard, the keyboard being coupled to the host device and being provided for entering logic data to the second data memory circuit; an input/output circuit, the input/output circuit being coupled to the keyboard and to the second data memory circuit; a display, the display being electrically coupled to and responsive to the output signals of the third signal receiving circuit, the first file length and content check circuit, the eighth signal receiving circuit and the ninth signal receiving circuit; and a discharge and recharge circuit, the discharge and recharge circuit forming a portion of the multiple computer receptacle device and being electrically coupled to the at least one pen based computer and responsive to the ninth signal.
 6. In combination:a plurality of pen based computers, each pen based computer including a battery, a display and an unlighted pen for handwritten input of information on the display; and apparatus for transferring data from the plurality of pen based computers, which comprises: a housing; a support frame mounted in the housing, the support frame including means for supporting in parallel the plurality of pen based computers, the plural computer supporting means defining a plurality of parallel slots for receiving respective pen based computers, the support frame further including a first back panel, the first back panel being situated in proximity to the plural computer supporting means, the plural computer supporting means including a top plate and a bottom plate disposed opposite the top plate, the top and bottom plates being mounted on the support frame, each of the top and bottom plates having an exposed surface, the exposed surface of the top plate facing the exposed surface of the bottom plate, each of the top and bottom plates having formed in the exposed surface thereof a plurality of spaced apart, parallel channels, the channels formed in the bottom plate being opposite to and in alignment with corresponding channels formed in the top plate so that the top and bottom plates define a plurality of parallel computer receiving slots for receiving pen based computers; a plurality of data input/output connectors, each data connector being mounted on the first back panel and positioned thereon in alignment with a respective slot defined by the plural computer supporting means so that the data connectors are adapted to mate with corresponding data connectors mounted on the pen based computers; a plurality of power connectors, each power connector being mounted on the first back panel and positioned thereon in alignment with a respective slot defined by the plural computer supporting means so that the power connectors are adapted to mate with corresponding power connectors mounted on the pen based computers; circuit means coupled to the plurality of data input/output connectors for transmitting data to the plurality of pen based computers for storage of the data therein and for receiving data from the plurality of pen based computers; and means coupled to the power connectors for discharging and recharging the batteries of the pen based computers.
 7. A combination as defined by claim 6, wherein each of the top and bottom plates is formed from an anti-friction material to allow the pen based computers to slide easily into respective computer receiving slots.
 8. A combination as defined by claim 6, wherein the apparatus for transferring data further comprises a plurality of indicator lights, each of the indicator lights being situated in alignment with a corresponding computer receiving slot.
 9. A combination as defined by claim 6, wherein the apparatus for transferring data further comprises multiple color indicating means, the multiple color indicating means being situated in alignment with each of the computer receiving slots, the multiple color indicating means having a first color which indicates to an operator of the apparatus that a particular pen based computer situated in a computer receiving slot in alignment with the multiple color indicating means having the first color should not be removed from the computer receiving slot, and having a second color different from the first color which indicates to the operator that a particular pen based computer situated in a computer receiving slot in alignment with the multiple color indicating means having the second color may be removed from the computer receiving slot.
 10. In combination:apparatus for transferring data from a plurality of pen based computers, each of the plurality of pen based computers including a battery pack, a display and an unlighted pen for handwritten input of information on the display, which comprises: a housing; a support frame mounted in the housing, the support frame including means for supporting in parallel a plurality of pen based computers, the plural computer supporting means defining a plurality of parallel slots for receiving respective pen based computers, the plural computer supporting means including a top plate and a bottom plate disposed opposite the top plate, the top and bottom plates being mounted on the support frame, each of the two and bottom plates having an exposed surface, the exposed surface of the top plate facing the exposed surface of the bottom plate, each of the top and bottom plates having formed in the exposed surface thereof a plurality of spaced apart, parallel channels, the channels formed in the bottom plate being opposite to and in alignment with corresponding channels formed in the top plate so that the top and bottom plates define a plurality of parallel computer receiving slots for receiving pen based computers, the support frame further including a first back panel, the first back panel being situated in proximity to the plural computer supporting means; a plurality of data input/output connectors, each data connector being mounted on the first back panel and positioned thereon in alignment with a respective slot defined by the plural computer supporting means so that the data connectors are adapted to mate with corresponding data connectors mounted on the pen based computers; and a plurality of power connectors, each power connector being mounted on the first back panel and positioned thereon in alignment with a respective slot defined by the plural computer supporting means so that the power connectors are adapted to mate with corresponding power connectors mounted on the pen based computers; a battery pack charging rack, the battery pack charging rack including means for supporting in parallel a plurality of computer battery packs, the plural battery back supporting means defining a plurality of battery pack receiving slots, each slot being dimensioned to receive a respective battery pack of a pen based computer; a plurality of battery pack connectors, the battery pack connectors being positioned in alignment with respective battery pack receiving slots so as to be adapted to make an electrical connection with corresponding contacts of the battery packs when the battery packs are mounted in the battery pack receiving slots; circuit means coupled to the plurality of data input/output connectors for transmitting data to the plurality of pen based computers for storage of the data therein and for receiving data from the plurality of pen based computers; a discharge and recharge circuit, the discharge and recharge circuit being selectively electrically coupled to the apparatus for transferring data and to the battery pack charging rack; and means for selectively electrically coupling the discharge and recharge circuit to the apparatus for transferring data and to the battery pack charging rack.
 11. A method for transferring data from and to a plurality of pen based computers, each of the pen based computers including a battery, a display and an unlighted pen for handwritten input of information on the display, which comprises the steps of:mounting the plurality of pen based computers in a multiple computer receptacle device, the multiple computer receptacle device including a housing, a support frame mounted in the housing, the support frame including means for supporting in parallel the plurality of pen based computers, the plural computer supporting means defining a plurality of parallel slots for receiving respective pen based computers, the plural computer supporting means including a top plate and a bottom plate disposed opposite the top plate, the top and bottom plates being mounted on the support frame, each of the top and bottom plates having an exposed surface, the exposed surface of the top plate facing the exposed surface of the bottom plate, each of the top and bottom plates having formed in the exposed surface thereof a plurality of spaced apart, parallel channels, the channels formed in the bottom plate being opposite to and in alignment with corresponding channels formed in the top plate so that the top and bottom plates define a plurality of parallel computer receiving slots for receiving pen based computers, the support frame further including a first back panel, the first back panel being situated in proximity to the plural computer supporting means, a plurality of data input/output connectors, each data connector being mounted on the first back panel and positioned thereon in alignment with a respective slot defined by the plural computer supporting means so that the data connectors are adapted to mate with corresponding data connectors mounted on the pen based computers, a plurality of power connectors, each power connector being mounted on the first back panel and positioned thereon in alignment with a respective slot defined by the plural computer supporting means so that the power connectors are adapted to mate with corresponding power connectors mounted on the pen based computers, circuit means coupled to the plurality of data input/output connectors for transmitting data to the plurality of pen based computers for storage of the data therein and for receiving data from the plurality of pen based computers, and means coupled to the power connectors for discharging and recharging the batteries of the pen based computers; receiving first data from the plurality of pen based computers and storing the first data in the multiple computer receptacle device; transmitting second data to the plurality of pen based computers and storing the second data in the pen based computers; and discharging and recharging the batteries of the pen based computers. 